Optical pickup device

ABSTRACT

In an optical pickup device, a side surface parallel in the optical axis direction of an optical component is respectively fixed with an adhesive at wall surfaces (internal walls) provided opposing with each other of an accommodation case. In a part of the wall surfaces of the accommodation case, a recessed channel to be filled with the adhesive is formed. The recessed channel is provided with a stepped portion along the optical axis of the optical component at the wall surfaces of the accommodation case. A gap between the relevant side surfaces and the side surface of the optical component is formed to be reduced symmetrically toward both end portions from the center in the optical axis direction of the optical component. Accordingly, bonding strength is never lowered and position of the optical pickup device is stably maintained in an optical system.

CLAIM OF PRIORITY

The present application claims priority from Japanese applicationJP2006-281050 filed on Oct. 16, 2006, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an optical pickup device for recordingand reproduction of an optical storage medium such as CD and DVD, etc.

(2) Description of the Related Art

An optical pickup device used for recoding and reproduction in anoptical disk drive apparatus utilizing an optical recording medium(optical disk) such as CD and DVD is arranged to be movable in theradius direction of the disk while it is facing to the surface ofoptical disk in the upper and lower directions. A structure of theoptical pickup device includes, at the interior of an accommodation casethereof, a light emitting element such as a laser diode, an opticalsystem for guiding the light emitted from the light emitting element toan objective lens via various lenses, prism, and mirror, etc. to focusthe light on an optical recording medium, and a photoelectric conversionelement for converting the received light into an electrical signal. Ofthese elements, optical components such as various lenses are fixed tothe accommodation case of the optical pickup device using an adhesivefor the arrangement at the optimum position on each light path when thelight is received. In this case, when the optical pickup device isformed thick (the size in the vertical direction to the surface ofrecording medium), both side surfaces and the bottom surface of theoptical components may be bonded to the accommodation case. However, ifthe optical pickup device is formed thin not resulting in the space forbonding to the bottom surface, only both side surfaces of the opticalcomponent are bonded to the accommodation case.

Japanese Patent Application Laid-Open Publication No. H11-110800discloses a mounting structure wherein the optical component forfocusing the optical beam to the optical disk is bonded at both sidesurfaces thereof. According to the mounting structure of this JapanesePatent Application Laid-Open Publication No. H11-110800, a filling partof the adhesive for bonding the optical component at the internalcircumferential surface of a mounting opening to which the opticalcomponent is mounted is formed in the depth corresponding to theintermediate part in the thickness direction of the mounting opening,namely formed in the step-by-step structure. Moreover, Japanese PatentApplication Laid-Open Publication No. H11-110800 further describes thatthe optical component can be bonded and fixed stably as a result in themanner that the adhesive is adhered only to the side surface of theoptical component and never diffuses to the rear surface side and frontsurface side for the optical component inserted into the mountingopening.

SUMMARY OF THE INVENTION

In the case where only both sides of an optical component are bondedwithin an accommodation case of an optical pickup, problems that bondingstrength may be lowered and an optical axis may be deviated due togradual progress in peeling at the bonding interface are easilygenerated, because stress generated by change in the environment such astemperature rise is applied in direct to the bonding part. Therefore,even in the case where only both sides of the optical component arebonded to the accommodation case, bonding and fixing technology forstably holding positional accuracy is required without any lowering ofbonding strength.

In the technology described in Japanese Patent Application Laid-OpenPublication No. H11-110800, an optical component can be bonded and fixedin the predetermined condition with reference to the bottom surface ofan opening and therefore the front and rear surfaces are nevercontaminated with an adhesive. However, it is difficult to stablymaintain positional accuracy of the optical component for change inenvironment such as temperature rise, etc. A reason is that mountingstructure of the optical component including a filling part isnon-symmetrical in both upper and lower directions. Namely, when anadhesive is thermally expanded, a compressing force to the opticalcomponent is never balanced in the bottom surface side and the uppersurface side. Moreover, when a mounting member is thermally expanded, itlifts up the optical component only in the upper direction. Accordingly,mispositioning may easily be generated in the upper and lower directions(optical axis direction).

Japanese Patent Application Laid-Open Publication No. H11-110800 doesnot relate to a structure that an optical component is bonded in directto an accommodation case but to a structure that an optical component isbonded to a mounting member which may be adjusted in the mountingposition with a drive mechanism (biaxial actuator). Therefore, even ifthe optical component is displaced in the upper and lower directionswith environmental change, such mispositioning can be absorbed withpositional adjustment. Moreover, since Japanese Patent ApplicationLaid-Open Publication No. H11-110800 discloses a structure based on thatan optical component is mounted by inserting the same into a mountingopening from the upper direction, it is difficult to employ a mountingstructure that a recessed filling part is provided at the intermediatepart in a vertically symmetrical shape. In addition, in the case of thevertically symmetrical structure, hardening is likely to becomeinsufficient, on the occasion that a adhesive is hardened with theultraviolet ray, because the ultraviolet ray is irradiatedinsufficiently to the adhesive at the recessed filling part.

A bonding and fixing technology described in the present invention isbased, in view of realizing low cost and reduction in thickness of anoptical pickup device, on that an optical component is bonded in directto an accommodation case and positional adjustment is not performedafter the bonding process.

Therefore, an object of the present invention is to provide an opticalpickup device for stably maintaining positional accuracy withoutlowering of bonding strength even in the case where only both sides ofthe optical component are bonded to the accommodation case.

The optical pickup device of the present invention includes an objectivelens for condensing and radiating an optical beam to an opticalrecording medium, an optical component for transmitting the optical beamamong a light emitting element, a photoelectric converting element, andthe objective lens and having an optical axis within the plane parallelto an optical pickup device placing surface, and an accommodation casefor accommodating the objective lens and the optical component andadhesively fixing the side surface parallel to the optical axisdirection of the optical component with an adhesive. Moreover, theadhesive fixing structure may be attained by making smaller a gap (a) atboth end portions in the optical axis direction than a gap (b) at thecenter in the optical direction in regard to a gap for bonding between aside surface to be bonded of the optical component and a side surface tobe bonded of the accommodation case provided opposing to the sidesurface of the optical component.

Here, a recessed channel to be filled with an adhesive is formed at thecenter in the optical axis direction to the side surface to be bonded ofat least any of the accommodation case or the optical component. Therecessed channel to be filled with the adhesive is constituted in themanner that a stepped portion thereof is formed as a sloping surface anda gap for bonding is formed to become smaller almost symmetricallytoward both end portions from the center in the optical axis direction.Moreover, the recessed channel to be filled with the adhesive is formedthrough the accommodation case or the optical component in the heightdirection thereof. The adhesive fills the recessed channel covering thesame and is also formed to the region, except for the circumference ofthe side surface of the optical component.

According to an aspect of the present invention, since an opticalcomponent may be held in a stable positional accuracy thereof withoutlowering of bonding strength even in the case where only both sides ofthe optical component are bonded in direct to the accommodation case,stable performance can be provided even for environmental change.

BRIEF DESCRIPTION OF THE DRAWINGS

These and objects as well as advantages of the present invention willbecome clear by the following description of preferred embodiments ofthe present invention with reference to the accompanying drawings,wherein:

FIG. 1 is a decomposed structural perspective view (first embodiment)showing an embodiment of an optical pickup device in relation to thepresent invention;

FIGS. 2A to 2C are diagrams (second embodiment) showing an example of abonding structure of an optical component 1 and an accommodation case 2in FIG. 1;

FIGS. 3A and 3B are diagrams showing an example of a forming region ofan adhesive 3 in FIG. 2;

FIGS. 4 a to 4G are diagrams (third embodiment) showing the otherexamples of a bonding structure of the optical component 1 and theaccommodation case 2 in FIG. 1;

FIGS. 5A to 5D are diagrams (fourth embodiment) showing the otherexample of a bonding structure of the optical component 1 and theaccommodation case 2 in FIG. 1;

FIGS. 6A and 6B are diagrams showing an example of a forming region ofan adhesive 3 in FIGS. 5A to 5D;

FIGS. 7A to 7C are diagrams (fifth embodiment) showing the other exampleof a bonding structure of the optical component 1 and the accommodationcase 2 in FIG. 1; and

FIGS. 8A and 8B are diagrams (sixth embodiment) showing the otherexample of a bonding structure of the optical component 1 and theaccommodation case 2 in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be describedwith reference to the accompanying drawings.

First Embodiment

FIG. 1 is a decomposed structural perspective view showing a preferredembodiment of an optical pickup device 100 of the present invention. InFIG. 1, the optical pickup device of the present invention is built intoan optical disk drive 101. The optical pickup device 100 fixes anoptical component 1 of various kinds, a light emitting element 11 suchas a laser diode, a photoelectric converting element 12, and anobjective lens 13, etc. by mounting these elements to an accommodationcase 2 (also defined as an accommodation case). An optical beam emittedfrom the light emitting element 11 is transmitted to the objective lens13 via the optical component 1 of various kinds and is then condensedand radiated to an optical recording medium (optical disk) 102 providedopposed to the objective lens 13. Moreover, a reflected light from theoptical disk 102 is condensed with the objective lens 13, transferred tothe photoelectric converting element 12 via an optical component 1 ofvarious kinds and then converted into an electric signal. In this case,an optical path (optical axis) for each optical component 1 is formedwithin a plane almost parallel to a surface of the optical disk 102, inother words, within a plane parallel to a placing surface of the opticalpickup device 100 (or accommodation case 2) as will be understood fromarrangement in FIG. 1. The optical pickup device 100 is driven with amotor not shown and moves in the radius direction of the optical disk102 along a guide rail 14.

The optical component 1 includes various lenses such as a grating lens,a coupling lens, and a detector lens. These lenses give large influenceon an optical transmission characteristic and must be maintained inhigher positional accuracy at the optimum position on the optical path.Therefore, the optical component 1 fixed in direct with an adhesivesupplied to the predetermined position of an accommodating part 20 inthe accommodation case 2. In this case, in view of reduction inthickness of the optical disk drive 101, the optical pickup device 100is formed thin through restriction on height and thickness (depth ofaccommodating part 20) thereof. Accordingly, each optical component 1 isconstituted in the structure that it cannot be bonded in the bottomsurface side and is bonded to the internal circumferential surface ofthe accommodation case 2 only at both side surfaces.

Various lenses considered as the optical component 1 are constitutedwith a die casting material mainly formed of any material of at leastpolyolefin and acryl. The accommodation case 2 is constituted with a diecasting material mainly formed of any material of at least Zn, Mg, Al,and PPS (polyphenylen sulfide). Moreover, as an adhesive, a materialthat is hardened with irradiation of ultraviolet ray is used. Thismaterial is supplied into a gap between the optical component 1 and theaccommodation case 2. This adhesive may be hardened, for example, withirradiation of the ultraviolet ray from the upper direction or the lowerdirection of the accommodation case 2.

For the optical pickup device 100, tolerance for mispositioning of theoptical component 1 becomes more severe with further improvement inperformance and thickness. Meanwhile, with further improvement inperformance, heat generated from each optical element increases inquantity. If such heat is transferred to the adhesive 3 and the opticalcomponent 1 via the accommodation case 2, stress due to difference inthe thermal expansion coefficients of members may be generated in theadhesive 3. Particularly, since the thin optical pickup device 100described above has a structure that only both side surfaces of theoptical component 1 are fixed to the accommodation case 2 with theadhesive 3, stress of the adhesive 3 increases. Such stress of theadhesive 3 is also generated with an environmental load. Such stressesbring about peeling and reduction in strength of the adhesive 3 and alsocause mispositioning of the optical component 1. Therefore, it has beenrequested to provide a structure that can reduce as much as possiblesuch stresses and does not easily generate mispositioning even ifstresses are generated.

Second Embodiment

FIGS. 2A to 2C are diagrams showing an example of a bonding structure ofthe optical component 1 and the accommodation case 2 in the opticalpickup device of FIG. 1.

FIG. 2A is a plan view observed from the upper part of the accommodationcase 2 (inserting side of the optical component 1). FIGS. 2B and 2C arecross-sectional views observed from the plane perpendicular to theoptical axis. The optical component 1 is arranged to the optimumposition for the optical axis 10 within the accommodation case 2 and theside surfaces 1 s in both sides parallel to the optical axis 10 of theoptical component 1 and each side surface 2 s of the accommodation caseprovided opposing to both side surfaces are bonded and fixed with theadhesive 3. In this case, a plane 1 p in the optical axis direction ofthe optical component 1 is not in contact with a plane 2 p in theoptical axis side of the accommodation case 2 and are arranged inseparation. In the arrangement described above, the optical pickupdevice of this embodiment is formed in the structure that stress of theadhesive 3 is reduced as much as possible even when environmental changeoccurs and that mispositioning (particularly, mispositioning in theoptical axis direction) of the optical component 1 is not easilygenerated even if stress is generated.

In this embodiment, a recessed channel 4 to be filled with the adhesiveis formed through the accommodation case 2 in the height (depth)direction at the center of the bonding surface in the optical axisdirection for the side surface 2 s as the bonding surface of theaccommodation case 2 as shown in FIG. 2A. As a result, a larger bondinggap (b) for the optical component 1 is attained at the center in theoptical axis direction as shown in the cross-section along A-A′ in FIG.2B, while a smaller bonding gap (a) is attained at the end part in theoptical axis direction as shown in the cross-section along B-B′ in FIG.2C (a<b). In more concrete, the gap (a) equal to or less than 1 mm ispreferable. Naturally, the adhesive 3 supplied to fill the gap is formedthick at the center and formed thin at the end part. In this case, therecessed channel 4 is formed in the shape to the stepped portion as asloping surface and the side surface 2 s to be bonded is formed in theshape almost symmetrical in the optical axis direction. Accordingly, thegap for bonding is made smaller almost symmetrically toward both endportions from the center in the optical axis direction.

According to the structure of the bonding surface in this embodiment,peeling of bonded area can be prevented by remarkably reducing stressthat is assumed as a reason of peeling at the bonded area, becausethickness of adhesive at the end part of the bonding surface (=a) isthinner than that in the structure of the related art where the bondinggap is formed in the uniform width. Moreover, since the adhesive at thecenter of the bonding surface (=b) is formed thick, sufficient bondingstrength of the adhesive for the coated region and the optical component1 can be assured. Furthermore, since the accommodation case 2 and itsbonding surface for the optical component 1 are shaped almostsymmetrically toward both end portions in the optical axis direction, ifeach member generates thermal expansion due to temperature change,expansion forces of these elements are balanced and therefore theoptical component 1 is never mispositioned in the optical axisdirection. In addition, since the surface 1 p of the optical component 1in the optical axis direction is never in contact with the surface 2 pof the accommodation case 2, the optical component 1 is nevermispositioned in the optical axis direction, even if the accommodationcase 2 is thermally expanded.

Moreover, in this embodiment, the recessed channel 4 is shaped to formthe stepped portion thereof as the sloping surface. Namely, the recessedchannel 4 is formed to bring about the width (c) at the upper end of thesloping surface that is larger than the width (d) at the lower end ofthe sloping surface (c>d). Therefore, thickness of the adhesive at thestepped portion of the recessed channel 4 is gradually reduced tofurther reduce the stress thereof. Accordingly, peeling of the bondedarea, reduction in bonding strength, and mispositioning of the opticalcomponent 1 resulting from such phenomena due to formation of therecessed channel can be prevented.

Moreover, the recessed channel 4 is formed through the depth directionof the accommodation case 2 in the identical shape of the cross-section.Accordingly, the ultraviolet ray is irradiated along the direction ofthe recessed channel 4 from the upper or lower direction of theaccommodation case 2 to equally irradiate the adhesive 3 supplied tofill the gap. As a result, not only the stable hardening characteristicof the adhesive 3 can be assured but also easier hardening work of theadhesive can be achieved. Here, it may be possible that the recessedchannel 4 is not formed through the depth direction of the accommodationcase 2 and is formed in the identical shape of cross-section at leastwithin the range of the bonding region. In this case, the ultravioletray is irradiated only from the selected one direction.

As the adhesive 3, an acrylic or epoxy system adhesive that is hardenedwith radiation of the ultraviolet ray is preferable. Moreover, theadhesive having the glass transition temperature resulting in acomparatively lower bonding strength may also be used. In addition, inorder to improve the bonding strength, it is also preferable for thesurface of the bonding region of the accommodation case 2 that the Blastprocessing that is generally conducted for the die-casting material isimplemented to form fine crenelation in the average size of aboutseveral μm.

FIGS. 3A and 3B are diagrams showing an example of a forming region(bonding region) of the adhesive 3 in the bonding structure of FIGS. 2Ato 2C. FIG. 3A is a perspective view of the entire part of theaccommodation case 2. FIG. 3B is a perspective view showing the bondingregion 3 s at the side surface of the optical component 1 after theaccommodation case 2 is removed. The adhesive 3 is never formed to theentire surface of the side surface is of the optical component 1 but isformed in the region other than the periphery of the side surface is.Namely, when sizes of the side surface is of the optical component 1 aredetermined that length in the optical axis direction is (k) and heightis (h), and when sizes of the region 3 s corresponding to above sizesare (e), and (f), respectively, relationships of e<k and f<h aredetermined. Therefore, the adhesive 3 is never adhered to the peripheralpart of the side surface is, not deteriorating the surface 1 p in theoptical axis side of the optical component 1.

In addition, it is preferable that the region 3 s is formed to satisfythe relationship of e>f for the sizes e and f. Namely, in the case wherethe size (e) in the optical axis direction of the region 3 s of theadhesive is determined larger, the adhesive 3 is fully supplied coveringthe recessed channel 4 in the width direction thereof and bondingstrength can be stabilized under the condition that the adhesive 3reaches the region where the bonding gap=(a) is achieved. These sizes ofthe bonding region 3 s may be controlled with amount of supply andsupply position of the adhesive 3.

Third Embodiment

FIGS. 4A to 4G are plan views showing the other example of the bondingstructure of the optical component 1 and the accommodation case 2 in theoptical pickup device of FIG. 1. Like the second embodiment, therecessed channel 4 to be filled with the adhesive is formed in theheight (depth) direction through the side surface to be bonded of theaccommodation case 2. In this third embodiment, the recessed channel 4is formed in various shapes. The bonding gap (b) at the center in theoptical axis direction and the bonding gap (a) at both end portions arestructured to result in the relationship of a<b and the adhesive fixingprocess is conducted using the adhesive 3.

In FIG. 4A, the recessed channel 4 is formed in the shape of characterV, while in FIG. 4B, the recessed channel 4 is formed in thesemi-elliptical shape, while in FIG. 4C, the recessed channel 4 isformed in the semi-circular shape. In FIG. 4D, the saw-tooth shapecrenelation is provided at the bonding surface and the bonding gaps (a)and (b) are determined as the average values of crenelation. In FIG. 4E,the stepped portion of the recessed channel 4 is formed as the sharpsloping surface (namely, difference in sizes (c) and (d) is setextremely small). In FIG. 4F, width (c) of the recessed channel 4 is setin the relation of c<g for the shortest lens-to-lens distance (g) in theoptical axis direction of the optical component 1. Moreover, in FIG. 4G,a size (e) in the optical axis direction of the region that is filledwith the adhesive 3 is limited up to both sloping positions of therecessed channel 4 (namely, e<c).

Even in these examples of structure, since the adhesive (=a) at both endportions of the bonding surface is formed thin, peeling of the bondedarea can be prevented by remarkably reducing stress that is consideredas a cause of peeling at the bonded area. Moreover, since the bondingsurface of the accommodation case 2 is formed almost symmetricallytoward both end portions of the bonding surface, expansion force of eachmember due to temperature change is well balanced and the opticalcomponent 1 is never mispositioned in the optical axis direction.

Fourth Embodiment

FIGS. 5A to 5D are diagrams showing the other example of the bondingstructure of the optical component 1 and the accommodation case 2. FIG.5A is a plan view observed from the upper direction of the accommodationcase 2, while FIGS. 5B and 5C are cross-sectional views observed fromthe plane perpendicular to the optical axis. In this fourth embodiment,the recessed channel 5 to be filled with the adhesive is formed throughthe optical component 1 in the height (depth) direction to the sidesurface 1 s of both sides as the bonding surface of the opticalcomponent 1. The side surface 2 s as the bonding surface of theaccommodation case 2 should be formed flat. As shown in FIG. 5A, therecessed channel 5 is formed at the center in the optical axis directionin the shape that the stepped portion is formed as the sloping surface.As a result, a large bonding gap (b) is given for the accommodation case2 at the center in the optical axis direction as shown in FIG. 5B, and asmall bonding gap (a) is given at the end part in the optical axisdirection as shown in FIG. 5C (a<b). Here, the recessed channel 5 mayalso be formed in the shape of each example of structure shown in thesecond embodiment or third embodiment. For example, length of thechannel 5 (size along the bonding surface 2 s of the accommodation case)may be set shorter then the radius of curvature of the lens formed tothe optical component 1 as shown in FIG. 5D.

FIGS. 6A and 6B are diagrams showing an example of the forming region(bonding region) of the adhesive 3. FIG. 6A is an entire perspectiveview of the accommodation case 2 and FIG. 6B is a perspective viewshowing the bonding region 3 s at the side surface of the opticalcomponent 1 after the accommodation case 2 is removed. Like the FIGS. 3Aand 3B described above, the adhesive 3 is not formed to the entiresurface of the side surface 1 s of the optical component 1 but is formedin the region 3 s other than the periphery. Moreover, when sizes of theregion are defined as (e) and (f), the adhesive 3 is preferably formedunder the condition satisfying the relationship of e>f.

In this embodiment, peeling of bonded area can be prevented byremarkably reducing stress that is a cause of peeling of the bondedarea, because thickness of the adhesive (=a) at the end part of thebonding surface is rather small. Moreover, since the bonding surface ofthe optical component 1 is formed in the shape almost symmetrical towardboth end portions of the bonding surface, expansion force of each memberdue to temperature change is well balanced and the optical component 1is never mispositioned in the optical axis direction.

Fifth Embodiment

FIGS. 7A to 7C are diagrams (plan views) showing the other example ofthe bonding structure of the optical component 1 and the accommodationcase 2 in the optical pickup device of FIG. 1. In this embodiment, therecessed channels 4, 5 to be filled with the adhesive are formed in bothside surface 2 s of the accommodation case 2 and the side surface is ofthe optical component 1. In FIGS. 7A and 7B, the recessed channels 4, 5have equal width, while in FIG. 7C, the recessed channels 4, 5 havedifferent widths. In any case described above, the larger bonding gap(b) is given at the center in the optical axis direction, while thesmaller bonding gap (a) is given at the end part in the optical axisdirection (a<b). This embodiment also provides the effect similar tothat of the embodiments described above. Moreover, depth of the recessedchannels 4, 5 that are required for obtaining the predetermined bondinggap (b) may be reduced to a half by forming the recessed channels toboth accommodation case 2 and the optical component 1.

Sixth Embodiment

FIGS. 8A and 8B are diagrams showing the other example of the bondingstructure of the optical component 1 and the accommodation case 2 in theoptical pickup device of FIG. 1, namely the cross-sectional viewsthereof observed from the optical axis direction. FIG. 8A is thecross-sectional view where the upper and lower corners 2 r of theaccommodation case 2 are angled (chamfered) in order to make easier theinserting work of the optical component 1. In this case, the recessedchannel is not shown but may be provided to any of the accommodationcase 2 and the optical component 1. The adhesive 3 is supplied to thegap between these elements avoiding the corners 2 r. FIG. 8B is thecross-sectional view where the side surface of the optical component 1is never formed flat and includes a projected part 1 t. In this case,bonding with the accommodation case 2 may be realized while theprojected part it is left as it is, by forming the recessed channel 4including the stepped portion that is equal to or larger than theprojected part it is formed in the side of the accommodation case 2.

The structure of optical pickup device and material of each memberdescribed in above embodiments are only an example. The structuresattained by modifying or combining as required the structures of theembodiments described above may also be considered as the objects of thepresent invention. The present invention may be adapted to the opticalpickup device using inorganic materials such as the other metalmaterials and glasses as the materials of the accommodation case and theoptical component.

Quality of recording and reproducing signals to and from an optical diskmay be improved and more stable performance may also be assured forenvironmental change by introducing the optical pickup device describedabove into an optical disk drive.

While we have shown and described several embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications asknown to those skilled in the art, and we therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

1. An optical pickup device arranged opposing to an optical recordingmedium to irradiate an optical beam emitted from a light emittingelement to the optical recording medium and to convert a reflected lightbeam into an electrical signal with a photoelectric converting element,the optical pickup device comprising: an objective lens for condensingand irradiating an optical beam to the optical recording medium; anoptical component for transferring the optical beam among the lightemitting element, the photoelectric converting element and the objectivelens and including an optical axis within a plane parallel to a placingsurface of the optical pickup device, and an accommodation case foraccommodating the objective lens and the optical component andadhesively fixing a side surface parallel to the optical axis directionof the optical component with an adhesive; wherein, adhesive fixing isconducted by setting a gap (a) at both end portions in the optical axisdirection smaller than a gap (b) at the center in the optical axisdirection in regard to a gap for bonding of a side surface to be bondedof the optical component and a side surface to be bonded of theaccommodation case provided opposing to the side surface of the opticalcomponent.
 2. The optical pickup device according to claim 1, wherein arecessed channel to be filled with the adhesive is formed at the centerin the optical axis direction to the side surface that is bonded with atleast any of the accommodation case and the optical component.
 3. Theoptical pickup device according to claim 2, wherein a stepped portion ofthe recessed channel to be filled with the adhesive is formed as asloping surface and the gap for bonding is constituted to become smallalmost symmetrically toward both end portions from the center in theoptical axis direction.
 4. The optical pickup device according to claim2, wherein the recessed channel to be filled with the adhesive is formedthrough the accommodation case or the optical component in the heightdirection.
 5. The optical pickup device according to claim 2, whereinthe adhesive is fully supplied covering the recessed channel and isformed in the region other than the periphery of the side surface of theoptical component.
 6. An optical pickup device arranged opposing to anoptical recording medium to irradiate an optical beam emitted from alight emitting element to the optical recording medium and to convert areflected optical beam into an electrical signal with a photoelectricconverting element, the optical pickup device comprising: an objectivelens for condensing and irradiating the optical beam to the opticalrecording medium; an optical component for transferring the optical beamamong the light emitting element, the photoelectric converting element,and the objective lens and including an optical axis within a planeparallel to a placing surface of the optical pickup device; and anaccommodation case for accommodating the objective lens and the opticalcomponent and adhesively fixing a side surface parallel to the opticalaxis direction of the optical component with an adhesive; wherein,adhesive fixing is conducted by setting thickness (a) at both endportions in the optical axis direction smaller than thickness (b) at thecenter in the optical axis direction in regard to thickness of theadhesive for bonding a side surface of the optical component and a sidesurface of the accommodation case provided opposing to the side surfaceof the optical component.
 7. The optical pickup device according toclaim 6, wherein the adhesive is formed in thickness that is reducedalmost symmetrically toward both end portions from the center in theoptical axis direction.